Absorption Lines in 4U 1630-472

Credit: Kubota et al. / ISAS/JAXA / Suzaku GOF

Absorption lines due to highly ionized iron observed from the
black hole X-ray transient system, 4U 1630-472
(
Kubota et al. (2007)). The top panel shows the data and the best-fit model
for all 6 observations, while lower panels show the residuals (data/model)
when the absorption lines are excluded for the individual observations.
The centroids of the absorption lines indicate that the absorber is in
fact an outflow. As the X-ray luminosity of 4U 1630-472 decreased
(from top to bottom), the 6.7 keV feature became noticeably stronger,
indicating a shift to lower ionization.